DVB-CBMS Phase 2 is standardizing a notification mechanism for delivering messages that contain information relevant to the user or terminal that is currently not conveyed via conventional channels. This notification mechanism can be used to inform the user or the mobile device about certain situations or situation changes, either related to a specific service or of a more general nature. Examples of service related notifications include the start of a certain TV show, the start of a specific item in a broadcast (e.g., the summary of a specific soccer match), or a specific notification in a live broadcast (e.g., an important moment in a sporting match: ‘swimmers are approaching finish line’). More general notifications include news items or stock tickers. Notifications can also be used to inform the mobile device itself to perform a certain action. For example, if the Electronic Service Guide (ESG) is updated, the device can receive an event about this and in turn gets the updated version.
The number of notification messages that are expected to be transmitted over DVB-H/DVB-Internet Protocol Data Cast (IPDC) can become very high, while a terminal or user might only be interested in a few of them. In this regard the DVB-CBMS group has defined a technical requirement for a mechanism to easily filter notification messages. However, whilst the technical requirement has been noted no implementation or embodiment has yet been proposed. The goal is to create a standard implementing efficient notification, such as DVB-IPDC version 2.0 or later.
A further consideration is that when the terminal is in a low-power mode (standby), the terminal may still want to receive some notifications to alert the user of important events. Therefore, efficient and low-power reception is an important goal to be achieved.
A trivial solution may be the insertion of a value in a predetermined location in the header of each message, such that the low-level hardware can filter on this value. Such a method is used for filtering the correct transport stream packets for a specific service in a DVB broadcast, known as PID filtering or service selection. However, as notification messages can contain many different kinds of information, filtering will only be useful if a notification message can contain a number of different filtering criteria. A method is needed to bring an efficient yet flexible approach to the transmission of notification messages.
The inventors recognising this problem devised the present invention.